Animals Flashcards

Question

A body cavity has many functions:

Answer 1

It's fluid cushions the internal organs, helping to prevent internal injury. The noncompressible fluid of the body cavity can function as a hydrostatic skeleton against which muscles can work. The presence of the cavity enables the internal organs to grow and move independently (stops organs adhering to each other or the muscle wall) of the outer body wall.

Answer 2

in their development. The molluscs, annelids, arthropods, and several other phyla belong to the protostomes, while echinoderms, chordates, and some other phyla belong to the deuterostomes. These differences centre on: cleavage pattern (how the mitotic cell division occurs), coelom formation (How does that fluid-filled space that’s surrounded by mesoderm form?), and blastopore fate (origins of mouth or the anus).

Answer 3

cleavage, in which planes of cell division are diagonal to the vertical axis of the embryo.

Answer 4

cleavage, where the fate of each embryonic cell is determined early in development.

Answer 5

cleavage in which the cleavage planes are parallel or perpendicular to the vertical egg axis. Most deuterostomes show indeterminate cleavage, whereby each cell in the early embryo retains the capacity to develop into a complete embryo.

Answer 6

Spiral cleavage, in which planes of cell division are diagonal to the vertical axis of the embryo.

Answer 7

Radial cleavage in which the cleavage planes are parallel or perpendicular to the vertical egg axis.

Answer 8

gastrula stage. As the archenteron forms in a protostome, solid masses of mesoderm split to form the coelomic cavities, called schizocoelous development. In deuterostomes, mesoderm buds off from the wall of the archenteron and hollows to become the coelomic cavities, called enterocoelous development.

Answer 9

the mouth and a second opening at the opposite end of the gastrula develops into the anus.

Answer 10

anus and the mouth is derived from the secondary opening.

Answer 11

porous bodies and choanocytes.

Answer 12

no true tissue.

Answer 13

neither radial or bilateral. No tissue layers – i.e. Parazoa.

Answer 14

closest to the colonial choanoflagellates.

Answer 15

loose federations of cells, which are not really tissues because the cells are relatively unspecialised. Sponges are sessile animals that lack nerves or muscles. However, individual cells can sense and react to changes in the environment.

Answer 16

a filter feeder, it pumps water/changes water currents to get food. Water is drawn through the pores into a central cavity, the spongocoel, and flows out through a larger opening, the osculum. More complex sponges contain branched canals and several oscula.

Answer 17

feeders, collecting food particles from water passing through food-trapping equipment. Flagellated choanocytes, or collar cells, line the spongocoel (internal water chambers) create a flow of water through the sponge with their flagella, and trap food with their collars.

Answer 18

two cell layers (not tissue layers, they do not have tissues) separated by a gelatinous region, the mesohyl. Wandering though the mesohyl are amoebocytes. They take up food from water and from choanocytes, digest it, and carry nutrients to other cells. These and sclerocytes secrete tough skeletal fibers within the mesohyl. Gives sponge structure but isn’t a hard skeleton. In some groups of sponges, these fibers are sharp spicules of calcium carbonate or silica. Other sponges produce more flexible fibers from a collagen protein called spongin.

Answer 19

both sperm and eggs. Gametes arise from choanocytes or amoebocytes. The eggs are retained, but sperm are carried out the osculum by the water current. Sperm are drawn into neighboring individuals and fertilize eggs in the mesohyl. The zygotes develop into flagellated, swimming larvae that disperse from the parent. When a larva finds a suitable substratum, it develops into a sessile adult.

Answer 20

the replacement of lost parts. They use regeneration not only for repair but also to reproduce asexually from fragments broken off a parent sponge.

Answer 21

cavity, and cnidocytes Eumetazoa – have true tissue. Radial symmetry. Diploblastic – two tissue layers. Neither acoelomate or coelomate, has a gastrovascular cavity.

Answer 22

Eumetazoa, the animals with true tissues. The oldest eumetazoan clade is the Radiata, animals with radial symmetry and diploblastic embryos. The two phyla of Radiata, Cnidaria and Ctenophora, may have had separate origins from different protozoan ancestors.

Answer 23

construction. They are a diverse group with over 10,000 living species, most of which are marine. The basic cnidarian body plan is a sac with a central digestive compartment, the gastrovascular cavity. It has muscle-like filaments to close and open mouth and to move but these are not true muscles.

Answer 24

and the floating medusa. The cylindrical polyps, such as hydras and sea anemones, adhere to the substratum by the aboral end and extend their tentacles, waiting for prey. Medusas (also called jellies) are flattened, mouth-down versions of polyps that move by drifting passively and by contacting their bell-shaped bodies. Some cnidarian exist only as polyps. Others exist only as medusas. Still others pass sequentially through both a medusa stage and a polyp stage in their life cycle.

Answer 25

capture prey and push the food into the gastrovascular chamber for digestion. Batteries of cnidocytes on the tentacles defend the animal or capture prey. Organelles called cnidae evert a thread that can inject poison into the prey, or stick to or entangle the target. Cnidae called nematocysts are stinging capsules.

Answer 26

cnidarians. Cells of the epidermis and gastrodermis have bundles of microfilaments arranged into contractile fibers. True muscle tissue appears first in triploblastic animals. When the animal closes its mouth, the gastrovascular cavity acts as a hydrostatic skeleton against which the contractile cells can work. Movements are controlled by a noncentralized nerve net associated with simple sensory receptors that are distributed radially around the body.

Answer 27

Hydrozoa, Scyphozoa, Cubozoa and Anthozoa.

Answer 28

Portuguese man of war, hydra and some corals. Mostly marine, most have both polyp and medusa stages, with polyp stage often colonial.

Answer 29

Jellyfish. All marine, medusa stage domanint and large with reduced polyp stage.

Answer 30

Sea anemones, sea fans, most corals. All marine, polyp stage domanint and medusa stage absent, many are colonial.

Answer 31

Box jellies and sea wasps. All marine, medusa stage dominant, box-shaped.

Answer 32

and medusa forms, as in the life cycle of Obelia. The polyp stage, often a colony of interconnected polyps, is more conspicuous than the medusas.

Answer 33

polyp form. When environmental conditions are favorable, a hydra reproduces asexually by budding, the formation of outgrowths that pinch off from the parent to live independently. When environmental conditions deteriorate, hydras form resistant zygotes that remain dormant until conditions improve.

Answer 34

Scyphozoa. The medusas of most species live among the plankton as jellies. Most coastal scyphozoans go through small polyp stages during their life cycle. Jellies that live in the open ocean generally lack the sessile polyp.

Answer 35

Anthozoa. They occur only as polyps. Coral animals live as solitary or colonial forms and secrete a hard external skeleton of calcium carbonate. Each polyp generation builds on the skeletal remains of earlier generations to form skeletons that we call coral (so a live polyp sits on top of a dead one).

Answer 36

Cubozoa. Life cycle includes a medusa and small polyp stage. Have small transparent cube shaped medusa form with at least four tentacles. More developed than Schyphozoa, more rapid and direct movement, more advanced nervous system and functioning eyes. Are among the most dangerous marine animals e.g. sea wasp.

Answer 37

Flatworms are acoelomates with gastrovascular cavities. Eumetazoa – have true tissue. Bilateral symmetry. Triploblastic – three tissue layers. Acoelomate – no body cavity.

Answer 38

are acoelomates with gastrovascular cavities.

Answer 39

the flukes and tapeworms.

Answer 40

middle embryonic tissue layer, mesoderm, which contributes to more complex organs and organs systems and to true muscle tissue.

Answer 41

cnidarians and ctenophores, flatworms have a gastrovascular cavity with only one opening (and tapeworms lack a digestive system entirely and absorb nutrients across their body surface). Unlike other bilaterians, flatworms lack a coelom (acoelomates).

Answer 42

Turbellaria, Monogenia, Trematoda, and Cestoidea.

Answer 43

free-living (nonparasitic) and most are marine. Planarians, members of the genus Dugesia, are carnivores or scavengers in unpolluted ponds and streams.

Answer 44

gas exchange and circulation. Their flat shape places all cells close to the surrounding water and fine branching of the digestive system distributes food throughout the animal. Nitrogenous wastes are removed by diffusion and simple ciliated flame cells help maintain osmotic balance.

Answer 45

cilia on the ventral epidermis, gliding along a film of mucus they secrete.

Answer 46

eyespots to detect light and lateral flaps that function mainly for smell. The planarian nervous system is more complex and centralised than the nerve net of cnidarians. Planarians can learn to modify their responses to stimuli.

Answer 47

regeneration. The parent constricts in the middle, and each half regenerates the missing end. Planarians can also reproduce sexually. These hermaphrodites cross-fertilise.

Answer 48

digestive system entirely and absorb nutrients across their body surface

Answer 49

Structural and behavioural adaptations. Parasites are specilised yet simplified. Complex life cycles. Intermediate hosts and larval reproduction.

Answer 50

animal harbouring the adult or sexually mature stage of the parasite.

Answer 51

the animal in which development occurs but in which adulthood is not reached

Answer 52

ectoparasites

Answer 53

endoparasites.

Answer 54

The monogeneans (Class: Monogenea), the trematodes (Class: Trematoda), and the Cestodes (Class: Cestoidea) as parasites in or on other animals. Many have suckers for attachment to their host. A tough covering protects the parasites. Reproductive organs nearly fill the interior of these worms.

Answer 55

Trematodes parasitise a wide range of hosts, and most species have complex life cycles with alternation of sexual and asexual stages. Many require an intermediate host in which the larvae develop before infecting the final hosts (usually a vertebrate) where the adult worm lives.

Answer 56

Fluke = flatworms

Answer 57

Hatches into this inside the snail… Then finds human host, penetrates their skin and blood vessels. The long tail falls off when they enter their host. Widely distributed throughout Africa, South America and some parts of Asia; distribution increasing with irrigation. Transmission occurs in fresh water where the cercaria (larval stage of Schistoma) comes in contact with and penetrates human skin. We have one in New Zealand called Duckage (caught from ducks); humans are an accidental host. Adult worms live within blood vessels of colon, small intestine and urinary bladder, releasing eggs into stool and urine which can end up in fresh water, hatch and metamorphose through an intermediate snail host to free-swimming cercaria which can penetrate human skin.

Answer 58

The large intestine wall)

Answer 59

bladder venules)

Answer 60

intestine venules)

Answer 61

Prevalent in the Far East; also in areas of Central America and Africa. Transmission is related to the consumption of raw freshwater crabs and crayfish which contain the larvae (metacercaria) of Paragonimus. It has two immediate hosts; the snail then the crab. Humans get infected by eating undercooked crab meat. Often asymptomatic. Variable incubation period at times years. Initially dry cough becoming productive of rusty to bloody sputum. Chest pain, pleuritic at times. Little fever; general health often unimpaired. Many different species of Paragonimus all with some different levels of human host adaptability. Eggs expectorated in sputum into fresh water hatch as ciliated miracidia which penetrate specific snails and multiply within. Free-swimming cercaria leave the snail and penetrate freshwater crabs and crayfish, infecting any that consume them. The consumed metacercaria penetrate the human small intestine wall and migrate to the lungs, where they mate and live for a number of year,s laying eggs which are expectorated or swallowed. Lung abscesses, chronic cough, rusty coloured sputum At times (~10%) aberrant worms end up in brain or in subcutaneous tissues. Prevention: Cooking crab meat, Sewage treatment

Answer 62

Clonorchis sinensis (China), Opisthorchis Estimates therefore vary widely between 20 000 and 200 000 deaths per year. (SE Asia) Opisthorchis felineus (Russia), Metorchis conjunctus (Canada) (intermediate host: freshwater fish); Fasciola spp (edible freshwater plants) worldwide. Infect more then 20 million esp. in far east. Acquired by eating infected freshwater fish or even freshwater plants. The adult , living in the intra-hepatic bile ducts releases eggs that, in stool, if reach fresh water will hatch as ciliated swimming miracidia. These infect specific snails, multiply and are released as swimming cercaria which infect freshwater fish (or edible plants in the case of Fasciola). If ingested by humans the larvae climb up the biliary tree (or cross the peritoneal cavity and liver parenchyma in the case of Fasciola) and mature to adults in the intrahepatic biliary radicles. Live for years in biliary tree producing obstruction and abdominal pain

Answer 63

fishes. Their life cycles are simple, with a ciliated, freeliving larva that starts an infection on a host. Have no intermediate host and have a ciliated larva called an Oncomiracidium While traditionally aligned with trematodes, some structural and chemical evidence suggests that they are more closely related to tapeworms. Usually occur on either the skin or gills of fish but some are endoparasites in the cloaca, oviducts or bladders of their hosts. Example: Polystoma integerrimum is a bladder parasite of frogs.

Answer 64

Lives as a parasite in the bladder of the common frog. Produces eggs when the frog spawns Larvae are attached to the internal gills of tadpoles (ectoparasite). When the tadpole metamorphoses into a frog its gills reabsorb and the parasite passes down the gut of the frog to the urinary bladder Matures at the end of 3 years – same as frog

Answer 65

Tapeworms) Tapeworms (class Cestoidea) are also parasitic. The adults live mostly in vertebrates, including humans. A flat, hermaphroditic, gutless freight train of a worm. Suckers and hooks on the head or scolex anchor the worm in the digestive tract of the host. A long series of proglottids, sacs of sex organs lie posterior to the scolex. Tapeworms absorb food particles from their hosts. No gut, but external surface is covered in microvillae. Maintains position in gut. Secretes chemicals that stop tapeworm form being digested. Absorbs food molecules. Mature proglottids, loaded with thousands of eggs, are released from the posterior end of the tapeworm and leave with the host’s feces. In one type of cycle, tapeworms eggs in contaminated food or water are ingested by intermediary hosts, such as pigs or cattle. The eggs develop into larvae that encyst in the muscles of their host. Humans acquire the larvae by eating undercooked meat contaminated with cysts. The larvae develop into mature adults within the human.

Answer 66

* Oligochaeta * Polychaeta * Hirudina

Answer 67

segmented worms. * All annelids (“little rings”) have segmented bodies externally and internally. * Annelids are protosomes that live the salt-water, moist freshwater habitats, and damp soil. * They have a true body cavity (a coelom) and are triploblastic. * Annelid body parts are repeated in each segment, each with own organs. This is known as METAMERISM * This group also show other advances over the more primitive animals - their efficient movement * They have antagonistic muscle layers * Circular * Longitudinal * They body separated into body segments * They have points of muscle attachment so as to apply force. The attachment of muscles to setae to aid in movement. * They have coelom, that forms a hydroskeleton for movement * Waves of muscular contraction pass down the body, enabling them to move (peristaltic movement). * Annelid worms are creeping and burrowing animals * They have a nervous system that coordinates waves of movement – giant fibers * Have advanced blood system that includes blood pigments * Also excretory system

Answer 68

system *Body moist -mucus and excretory discharge *Respiratory pigment

Answer 69

burrow in sand and silt. * Some aquatic annelids swim in pursuit of food.

Answer 70

annelid, is partitioned by septa, but the digestive tract, longitudinal blood vessels, and nerve cords penetrate the septa and run the animal’s length.

Answer 71

septal partitions (which allow fluid-filled separate segments) between segments. Each isolated coelomic space functions as a hydrostatic skeletal unit so that, when its longitudinal muscles are fully contracted, its circulars are fully stretched.

Answer 72

1. body segments at head and rear are thick - longitudinal muscles contract while circular muscles relax and anchor to the ground by bristles (setae). Other segments are long and thin. 2. Head moved forward because circular muscles in the head segments have contracted. Segments behind head and rear are now thick and anchored - stops worm slipping back. 3. Head segments are thick again and achored in new position. Rear segments have released from the ground and have been pulled forward. When the longitudinal muscles are contracted, the segments are narrow and the setae are protruding against the substratum. This anchors the segments so that the worm can advance. The sequence then alters, and the circular muscles contract, elongating the worm. Burrowing is similar to crawling, and muscles thrust the head into the soil, and the bulge just behind the head creates the burrow. Setae anchor the animal so that other parts of the body can extend.

Answer 73

Terrestrial and freshwater segmented worms. Reduced head, no parapodia but setae present.

Answer 74

Mostly marine segmented worms. Well-developed head, each segment usually has parapodia with setae; tube-dwelling, free-living

Answer 75

Leeches. Body usually flattened, woith reduced coelom and segmentation; setase absent, suckers at anterior and posterior ends; parasites, predators and savengers.

Answer 76

* The digestive system consists of a pharynx, an esophagus, crop, gizzard, and intestine. * The closed circulatory system carries blood with oxygen-carrying hemoglobin through dorsal and ventral vessels connected by segmental vessels. * The dorsal vessel and five pairs of esophageal vessels act as muscular pumps to distribute blood. * In each segment is a pair of excretory tubes, metanephridia, that remove wastes from the blood and coelomic fluid. * Wastes are discharged through exterior pores. * A brain like pair of cerebral ganglia lie above and in front of the pharynx. * A ring of nerves around the pharynx connects to a subpharyngeal ganglion. * Earthworms are cross-fertilizing hermaphrodites. * Two earthworms exchange sperm and then separate. * The received sperm are stored while a special organ, the clitellum, secretes a mucous cocoon. * As the cocoon slides along the body, it picks up eggs and stored sperm and slides off the body into the soil. * Some earthworms can also reproduce asexually by fragmentation followed by regeneration.

Answer 77

* Each segment of a polychaete (“many setae”) has a pair of paddlelike or ridgelike parapodia (“almost feet”) that function in locomotion. * Each parapodium has several chitinous setae. * In many polychaetes, the rich blood vessels in the parapodia function as gills. * Most polychaetes are marine. * Many crawl on or burrow in the seafloor. * A few drift and swim in the plankton. * Others live in tubes that the worms make by mixing mucus with sand and broken shells. * Polychaetes include carnivores, scavengers, and planktivores. * The brightly coloured fanworms trap plankton on feathery tentacles.

Answer 78

segments in exactly the same phase of contraction is usually from eleven to fifteen segments in length.

Answer 79

eight segments long, and in swimming (D) the "wave-length" increases to about forty segments. Uses muscular contraction of long muscles.

Answer 80

* The majority of leeches inhabit fresh water, but land leeches move through moist vegetation. * Leeches range in size from about 1 to 30 cm. * Many leeches feed on other invertebrates, but some blood-sucking parasites feed by attaching temporarily to other animals, including humans. * Some parasitic species use bladelike jaws to slit the host’s skin, while others secrete enzymes that digest a hole through the skin. * The leech secretes hirudin, an anticoagulant, into the wound, allowing the leech to suck as much blood as it can hold. * Until this century, leeches were frequently used by physicians for bloodletting. * Leeches are still used for treating bruised tissues and for stimulating the circulation of blood to fingers or toes that have been sewn back to hands or feet after accidents.

Answer 81

* Leeches are structurally more complex and more specialised than other annelids, but are mechanically simpler * They have no septa * They have 34 segments without setae * The coelom is continuous, and so is a fluid-filled bag * Most do a simple creeping action (looping) Locomotion in an artificially marked leech. Note that when the leech is at its most elongate and thinnest the circular muscles are fully contracted and that when the leech is shortest and thickest the longitudinal muscles are fully contracted. The leech is a fluid-filled bag of unchanging volume, and the longitudinal and circular muscles act antagonistically around this hydrostatic skeleton Piscicola looping movement: Attaches by post sucker, extends body (circular muscles), attaches anterior sucker, repositions posterior sucker, contracts (longitudinal muscles) shortens body pulling body towards anterior sucker. Touches the side of itself before reattaching then loops out to repeat the cycle again.

Answer 82

* The coelom provides a hydrostatic skeleton that allows new and diverse modes of locomotion. * It also provides body space for storage and for complex organ development. * The coelom cushions internal structures and separates the action of the body wall muscles from those of the internal organs, such as the digestive muscles. * Segmentation allows a high degree of specialisation of body regions. * Groups of segments are modified for different functions.

Answer 83

muscular foot, a visceral mass, and a mantle

Answer 84

* Polyplacophora * Gastropoda * Bivalvia * Cephalopoda

Answer 85

150,000 known species of diverse forms, including snails and slugs, oysters and clams, and octopuses and squids.

Answer 86

marine, though some inhabit fresh water, and some snails and slugs live on land.

Answer 87

animals, but most are protected by a hard shell of calcium carbonate.

Answer 88

shells completely during their evolution.

Answer 89

plan with a muscular foot (typically for locomotion), a visceral mass with most of the internal organs, and a mantle.

Answer 90

shell, drapes over the visceral mass and creates a water-filled chamber, the mantle cavity, with the gills, anus, and excretory pores.

Answer 91

strap-like rasping organ, a radula, to scrape up food.

Answer 92

cephalisation (having a head end) and show complex behaviour

Answer 93

* Head and foot complex with nerves and locomotory organs * Visceral hump contains organs for digestion, reproduction, excretion * Mantle hanging form visceral mass and secreting shell * Space between mantle shell and visceral mass - mantle cavity. Contains gills (ctenidia) and canals from alimentary canal, excretory and genital system.

Answer 94

shell in 1 piece eg limpets, snails

Answer 95

shell forms 2 valves, eg mussels clams etc

Answer 96

eg squid, octopus – have no external shell

Answer 97

sexes, with gonads located in the visceral mass. * However, many snails are outcrossing hermaphrodites. * The life cycle of many marine mollusks includes a ciliated larvae, the trophophore. * This larva is also found in marine annelids (segmented worms).

Answer 98

Polyplacophora (chitons), Gastropoda (snails and slugs), Bivalvia (clams, oysters, and other bivalves), and Cephalopoda (squids, octopuses, and nautiluses).

Answer 99

* Other than cephalopods all Mollusca have an open circulatory System * The muscular heart pumps blood to all tissues via cavities known as hemocoel. * Cephalopods – closed circulatory system * Blood contained in vessels * More efficient – meets the demands of large organs e.g., brain.

Answer 100

* Chitons are marine animals with oval shapes and shells divided into eight dorsal plates. * Chitons use their muscular foot to grip the rocky substrate tightly and to creep slowly over the rock surface. * Chitons are grazers that use their radula to scrape and ingest algae. * In Chitons and most gastropods there is a foot with a flat creeping sole which has become adapted for locomotion over a variety of substrata.

Answer 101

* Most of the more than 40,000 species in the Gastropoda are marine, but there are also many freshwater species. * Garden snails and slugs have adapted to land. * During embryonic development, gastropods undergo torsion in which the visceral mass is rotated up to 180 degrees, such that the anus and mantle cavity are above the head in adults. * Most gastropods are protected by single, spiraled shells into which the animals can retreat if threatened. * While the shell is typically conical, those of abalones and limpets are somewhat flattened. * Other species have lost their shells entirely and may have chemical defenses against predators. * Many gastropods have distinct heads with eyes at the tips of tentacles. * They move by a rippling motion of their foot. * Most gastropods use their radula to graze on algae or plant material. * Some species are predators. * In these species, the radula is modified to bore holes in the shells of other organisms or to tear apart tough animal tissues. * In the tropical marine cone snails, teeth on the radula form separate poison darts, which penetrate and stun their prey, including fishes.

Answer 102

mucus (pedal gland)

Answer 103

ciliary propulsion

Answer 104

against a haemocoele hydrostatic skeleton – blood spaces within the tissue Longitudinal muscles Oblique muscles Transverse muscles

Answer 105

Movement is achieved by waves of muscular contractions passing along the foot. The foot remains in contact with the substratum by mucus.

Answer 106

Waves pass the same direction as the movement of the animal. Contractions of longitude muscles dorsal vemntral muscles.

Answer 107

Waves pass opposite direction to the movement. Contractrions of the trnasverse musckes followed by contraction of longitudinal muscles. Waves pass from anterior to posterior.

Answer 108

Each side of the foot is out of phase with the other side. Waves of muscular contraction in the precious example pass in one part of the floor, however, in some species they can occur on alternating sides of the foot.

Answer 109

gills that are used for feeding and gas exchange.

Answer 110

feeders, trapping fine particles in mucus that coats the gills. * Cilia convey the particles to the mouth. * Water flows into mantle cavity via the incurrent siphon, passes over the gills, and exits via the excurrent siphon.

Answer 111

* Bivalves have shells divided into two halves. * The two parts are hinged at the mid-dorsal line, and powerful adductor muscles close the shell tightly to protect the animal. * When the shell is open, the bivalve may extend its hatchet-shaped foot for digging or anchoring. * Most bivalves live rather sedentary lives. * Sessile mussels secrete strong threads that tether them to rocks, docks, boats, and the shells of other animals. * Calms can pull themselves into the sand or mud, using the muscular foot as an anchor. * Scallops can swim in short bursts to avoid predators by flapping their shells and jetting water out their mantle cavity. * In most species of bivalves, the foot is specialised for burrowing. * Burrowing is achieved by the interaction of the foot muscles (hydrostatic skeleton and the shell external skeleton)

Answer 112

clams, oysters, mussels, and scallops.

Answer 113

* Cephalopods use rapid movements to dart toward their prey which they capture with several long tentacles. * Squids and octopuses use beaklike jaws to bite their prey and then inject poison to immobilize the victim. * A mantle covers the visceral mass, but the shell is reduced and internal in squids, missing in many octopuses, and exists externally only in nautiluses. * Fast movements by a squid occur when it contracts its mantle cavity and fires a stream of water through the excurrent siphon. * By pointing the siphon in different directions, the squid can rapidly move in different directions. * The foot of a cephalopod (“head foot”) has been modified into the muscular siphon and parts of the tentacles and head. * Most octopuses live on the seafloor. * They creep and scurry using their eight arms in search of crabs and other food. * Cephalopods have an active, predaceous lifestyle. * Unique among mollusks, cephalopods have a closed circulatory system to facilitate the movements of gases, fuels, and wastes through the body. * They have a well-developed nervous system with a complex brain and well-developed sense organs. * This supports learning and complex behavior. * The ancestors of octopuses and squids were probably shelled mollusks that took up a predaceous lifestyle. * The loss of the shell occurred in later evolution. * Shelled cephalopods called ammonites were the dominant invertebrate predators for hundreds of millions of years until they perished in Cretaceous mass extinction. * Some were as large as truck tires.

Answer 114

* Arachnida * Diplopoda * Chilopoda * Insecta * Crustacea

Answer 115

coelomates with exoskeletons and jointed appendages. * This phylum of represented in nearly all habitats in the biosphere. * On the criteria of species diversity, distribution, and sheer numbers, arthropods must be regarded as the most successful animal phylum.

Answer 116

body segmentation, a hard exoskeleton, and jointed appendages. * Groups of segments and their appendages have become specialised for a variety of functions, permitting efficient division of labour among regions.

Answer 117

cuticle, an exoskeleton constructed from layers of protein and chitin. * The exoskeleton protects the animal and provides points of attachment for the muscles that move appendages. * It is thick and inflexible in some regions, such as crab claws, and thin and flexible in others, such as joints. * The exoskeleton of arthropods is strong and relatively impermeable to water. * To grow, an arthropod must molt (ecdysis) its old exoskeleton and secrete a larger one, a process that leaves the animal temporarily vulnerable to predators and other dangers.

Answer 118

eyes for vision, olfactory receptors for smell, and antennae for touch and smell. * Most sense organs are located at the anterior end of the animal, showing extensive cephalization.

Answer 119

circulatory system in which hemolymph fluid is propelled by a heart through short arteries into sinuses (the hemocoel) surrounding tissues and organs. * Hemolymph returns to the heart through valved pores. * The true coelom is much reduced in most species.

Answer 120

organs for gas exchange. * Most aquatic species have gills with thin feathery extensions that have an extensive surface area in contact with water. * Terrestrial arthropods generally have internal surfaces specialised for gas exchange. * For example, insect have tracheal systems, branched air ducts leading into the interior from pores in the cuticle.

Answer 121

* trilobites (all extinct) * chelicerates (horseshoe crabs, scorpions, ticks, spiders, and the extinct eurypterids) * uniramians (centipedes, millipedes, and insects) * crustaceans (crabs, lobsters, shrimps, barnacles, and many others)

Answer 122

* While chelicerates have claw like feeding appendages, chelicerae, uniramians and crustaceans have jawlike mandibles . * Chelicerates lack sensory antennae and most have simple eyes (eyes with a single lens), but uniramians and crustaceans have antennae and usually a pair of compound eyes (multifaceted eyes with many separate focusing elements) in addition to simple eyes. * While uniramians have a pair of antennae and uniramous (unbranched) appendages, crustaceans have two pairs of antennae and biramous (branched) appendages.

Answer 123

Chelicerates (sipders, scorpions, horseshoe crabs) * Claw like feeding appendages * Lack sensory antennae * Most have simple eyes (single lens) Uniramians (centipedes, millipedes, insects) * Jaw like mandibles * Have 1 pair of antennae * Compound eyes (multifaceted multiple lenes) * Unbranched appendages Crustaceans (crabs, lobsters, shrimps, barnacles etc) * Jaw like mandibles * Have a 2 pair of antennae * Compound eyes (multifaceted multiple lenes) * Biramous (branched) appendages

Answer 124

exoskeleton While it initially evolved for protection and locomotion, on land the exoskeleton also solved problems of water loss because the cuticle is relatively impermeable to water, helping prevent desiccation. The firm exoskeleton also provided support when arthropods left the relative buoyancy of water.

Answer 125

wormlike with two pairs of walking legs on each of their many segments. * They eat decaying leaves and plant matter. * They may have been among the earliest land animals.

Answer 126

terrestrial carnivores. * The head has a pair of antennae and three pairs of appendages modified as mouthparts, including the jaw like mandibles. * Each segment in the trunk region has one pair of walking legs. * Centipedes have poison claws on the anterior most trunk segment that paralyse prey and aid in defense.

Answer 127

Arthropod is completely covered by the cuticle, an exoskeleton constructed from layers of protein and chiti * Exoskeleton – outside skeleton with muscles on the inside, eg, Arthropods * Endoskeleton – an internal skeleton, muscles attach to the outside, eg, bone

Answer 128

* 2 main layers 1. procuticle and 2. epicuticle * Cuticle also lines gut and respiratory organs of arthropods * Cuticle secreted by integumentary epithelial cells (hypodermis) * Epicuticle – proteins and in some, wax * Procuticle consists of exocuticle, endocuticle and mesocuticle all of which have protein and chitin bound by glycoprotein * In addition, the exocuticle is tanned – rigid. However, it is missing around joints of along lines where the animal will rupture during molting * Colouration of cuticle - melanin pigments or chromatophores

Answer 129

The outermost layer has wax and proteins embedded in it: This lipoprotein is secreted after moulting through pore canals. When the exoskeleton lacks a waxy epicuticle and is thin it is relatively permeable to gas and water.

Answer 130

Hard components - reduce water loss in air Allows mobility of the body - attachment of muscles, i.e. to the exoskeleton Provides protection

Answer 131

Prevents growth - moults (sheds outter layer) Requires special sense organs Prevents passage of material - both in and out of the body therefore needs special respiratory and excretory organs

Answer 132

1. Dorsal tergum 2. Ventral sternum 3. 2 lateral pleura

Answer 133

cuticle. 1. Muscles and cuticle act together as a leaver system 2. Extension on appendages occurs in part or entirely by an increase in blood pressure – the animals have an open blood system

Answer 134

coelomates with exoskeletons and jointed appendages.

Answer 135

They can walk with so many legs by preventing something called field overlaps. * During locomotion limbs move backwards and forwards * Effective stroke – leg in contact with ground, closer to body than recovery stroke * Recovery stroke – leg leaves ground swinging forward before next stroke. * This allows long animals such as centipedes and millipedes to walk with short legs * What happens if they need to go fast? * Need to increase the length of the stride to achieve this need to increase length of limb * Problems with moving fast: * Field overlaps * Mechanical interference

Answer 136

Flight. Flying animals can escape many predators, find food and mates, and disperse to new habitats faster than organisms that must crawl on the ground.

Answer 137

side of the thorax. * Wings are extensions of the cuticle and are not true appendages. * Several hypotheses have been proposed for the evolution of wings. * In one hypothesis, wings first evolved as extensions of the cuticle that helped the insect absorb heat and were later modified for flight. * A second hypothesis argues that wings allowed animals to glide from vegetation to the ground. * Alternatively, wings may have served as gills in aquatic insects. * Still another hypothesis proposes that insect wings functioned for swimming before they functioned for flight.

Answer 138

* Up and down movement alone is not sufficient for flight. * Wings must, at the same time, be move forward and backward * The complete cycle of a single wing beat either describes an ellipse (grasshopper), or a figure of eight (bees and flies) * During a wing cycle the wings are held at different angles to provide lift and thrust. * Deviations, in flight path because of rolling, pitching or yawing are correct for by changing the wing position during flight.

Answer 139

They occur in some invertebrate groups (Echinoderms and Sponges) but are best developed in vertebrates

Answer 140

* Support - in air or water * Protection – brain and internal organs * Movement – for muscles to attach and act as levers against

Answer 141

phylum Chordata, which includes the vertebrates. * However, these animals share the deuterostome characteristics of radial cleavage, development of the coelom from the archenteron, and the formation of the anus from the blastopore. * These developmental features that define the Deuterostomia are supported by molecular systematics.

Answer 142

Echinoderms have a water vascular system and secondary radial symmetry. * Sea stars and most other echinoderms are sessile, or slow-moving animals. * The internal and external parts of the animal radiate from the center, often as five spokes. * A thin skin covers an endoskeleton of hard calcareous plates. * Most echinoderms are prickly from skeletal bumps and spines that have various functions. * Unique to echinoderms is the water vascular system, a network of hydraulic canals branching into extensions called tube feet. * These function in locomotion, feeding, and gas exchange. * Sexual reproduction in echinoderms usually involves the release of gametes by separate males and females into the seawater. * The radial adults develop by metamorphosis from bilateral larvae. * The radial appearance of most adult echinoderms is the result of a secondary adaptation to a sessile lifestyle. * Their larvae are clearly bilateral and even echinoderm adults are not truly radial in their anatomy.

Answer 143

* Asteroidea (sea stars) * Ophiuroidea (brittle stars) * Echinoidea (sea urchins and sand dollars) * Crinoidea (sea lilies and feather stars) * Holothuroidea (sea cucumbers) * Concentricycloidea (sea daisies)

Answer 144

arms (sometimes more) radiating from a central disk. * The undersides of the arms have rows of tube feet. * Each can act like a suction disk that is controlled by hydraulic and muscular action. * Sea stars use the tube feet to grasp the substrate, to creep slowly over the surface, or to capture prey. * When feeding on closed bivalves, the sea star grasps the bivalve tightly and everts its stomach through its mouth and into the narrow opening between the shells of the bivalve. * Enzymes from the sea star’s digestive organs then begin to digest the soft body of the bivalve inside its own shell. * Sea stars and some other echinoderms can regenerate lost arms and, in a few cases, even regrow an entire body from a single arm. * Brittle stars (class Ophiuroidea) have a distinct central disk and long, flexible arms. * Their tube feet lack suckers. * They move by serpentine lashing of their arms. * Some species are suspension-feeders and others are scavengers or predators.

Answer 145

arms, but they do have five rows of tube feet that are used for locomotion. * Sea urchins can also move by pivoting their long spines. * The mouth of an urchin is ringed by complex jawlike structures adapted for eating seaweed and other foods. * Sea urchins are roughly spherical, while sand dollars are flattened and disk-shaped.

Answer 146

sea lilies that are attached to the substratum by stalks and feather stars that crawl using their long, flexible arms. * Both use their arms for suspension-feeding. * Crinoids show very conservative evolution. * Fossilized sea lilies from 500 million years ago could pass for modern members of the class.

Answer 147

echinoderms. * They lack spines, the hard endoskeleton is much reduced in most, and the oral-aboral axis is elongated. * However, they do have five rows of tube feet, like other echinoderms and other shared features. * Some tube feet around the mouth function as feeding tentacles for suspension-feeding or deposit feeding

Answer 148

fluid held under pressure in a closed body compartment. * Form and movement is controlled by changing the shape of this compartment. * The hydrostatic skeleton of earthworms allow them to move by peristalsis. * Advantageous in aquatic environments and can support crawling and burrowing. * Does not allow for running or walking.

Answer 149

surface of an animal. * Mollusks are enclosed in a calcareous exoskeleton. * The jointed exoskeleton of arthropods is composed of a cuticle. * Regions of the cuticle can vary in hardness and degree of flexibility. * About 30 – 50% of the cuticle consists of chitin. * Muscles are attached to the interior surface of the cuticle. * This type of exoskeleton must be molted to allow for growth.

Answer 150

soft tissues. * Sponges have spicules. * Echinoderms have plates composed of magnesium carbonate and calcium carbonate. * Chordate endoskeletons are composed of cartilage and bone. * The bones of the mammalian skeleton are connected at joints by ligaments. * Bone and cartilage are living tissue – connective tissue

Answer 151

Respiration includes four distinct processes concerned with acquiring oxygen (O2) and transforming it to energy: 1. Ventilation with water or air (“breathing”) 2. Gas exchange: Uptake of O2 from the environment and release of CO2 (body surface, gills, lungs) 3. Transport of gases between the respiratory organs and tissue (May involve a blood circulatory system) 4. Cellular metabolism Aerobic metabolism in the mitochondria consumes O2, produces CO2 and ATP (energy). The oxygen transformation may or may not involve a circulatory system.

Answer 152

how much oxygen is consumed.

Answer 153

* Problem: – Need to get O2 to cells * Solutions: – Take up O2 across the epithelial surface, transport it to the cells * Evolutionary consequences: – Selection favours efficiency: stronger selection where energy requirements (and therefore O2 requirements) are higher.

Answer 154

Compared to air, water is not a particularly good respiratory medium for animals, because: Low oxygen content High density and viscosity

Answer 155

A. Cutaneous diffusion only (body surface, skin) B. Cutaneous diffusion plus circulatory system (blood) C. Gills plus circulatory system External gills Water “lungs” Internal gills

Answer 156

Gas exchange just occurs across the skin Diffusion Oxygen diffuses across the skin.

Answer 157

net movement of a substance from a high to a low concentration due to the random thermal motion of molecules. The exchange of oxygen (O2) across cell membranes at the body surface and internal tissues occurs by diffusion. Diffusion is usually expressed in terms of partial pressure (think in terms of concentration)

Answer 158

Fick’s law. The rate of diffusion of oxygen. Cutaneous diffusion only Krogh’s Constant for oxygen x area x partial pressure difference/thickness of diffusion barrier

Answer 159

- maximise area - maximise partial pressure - minimise thickness

Answer 160

~ 1mm thick for O2 to reach tissues by diffusion alone.

Answer 161

You’re limited in how big you can get. There is no scope to be able to develop larger organs. Oxygen also can’t get into deeper cell layers with just this so animals need to remain smaller and thinner.

Answer 162

Organisim doesn’t have to be flat. Lots of animals like sponges rely on diffusion. Quite large animals with a thin body wall surrounding a water-filled cavity can also supply oxygen by diffusion alone.

Answer 163

Via cutaneous diffusion

Answer 164

Gas exchange is still generally through the skin, but oxygen is moved to the tissues, not through diffusion, but by bulk flow (convection in the blood). The earthworm has ventral and dorsal blood vessels and pseudo hearts to pump the blood around.

Answer 165

The folds in this frog’s skin maximise the surface area for diffusion. Problems: thin surface for gas exchange conflicts with protective function, limited by available surface area (not all areas are suitable), limits size (surface area to volume ratio)

Answer 166

Gills are thin outgrowths of the body wall with high surface area, ventilated externally and perfused internally with blood. The ventilation can be passive, depending on the tides for example, or can be active where there’s an active pumping of water across the gills. There are three types of gills; external, internal and water lungs. Afferent vessels take blood to the organs, efferent vessels take blood away from the organs. Axolotals also have external gills, they are a type of salamander.

Answer 167

The most primitive type, found in sea urchins, star fish, but there are many species with external gills. Can also be on polychaetes. However, there are drawbacks. External gills are vulnerable to damage, parasites, and predation (if there is an attempt at predation, the gills can get easily damaged). They can cause drag when swimming. Difficult to ventilate efficiently.

Answer 168

These internalise the gas exchange. Water lungs: (tidally ventilated water-filled cavity) Found on sea cucumbers, called the respiratory tree (where water goes into, these contract to expel water. So water has to physically be moved in and out. Problems: Ventilation is energetically costly. Water is heavy. Reversing flow must overcome inertia.

Answer 169

They are energetically costly to ventilate

Answer 170

Lack of streamlining isn’t a problem now that they’re internal. They are enclosed in a brachial chamber, and these gills can be ventilated by unidirectional currents of water (tides and surges of the water). Much more efficient way of getting oxygen, which allows much more energy. Molluscs have these. Paua or abalone, Haliotis iris. Shell holes are exhalant, ventilated by cilia on gills and by surge currents

Answer 171

(scaphognathite) pumps water unidirectionally over the gills, which are enclosed within the branchial chamber. Things like crustaceans (crayfish, lobsters) actively move water across the gills. (In lobsters) The gills are attached to the leg bases, water enters through the leg bases and leaves through the side of the mouth.

Answer 172

1. The finger-like filaments on the gills (larger surface area) 2. The cuticle that govers the gills is very thin 3. They have these gill bailers that pumps water (gives uni-directional flow across the gills)

Answer 173

flow. Crabs also have brachial chambers just like lobsters, but in crabs, the gills are compressed into these flat plates, with, again, very thin cuticles. Water flows in one direction between the plates, inside the plates, and blood flows the opposite direction (this is the countercurrent).

Answer 174

fish. A feature fish has over the previous group (especially in bony fish) is the duel pump system and countercurrent gas exchange. A fish continually pumps water through its mouth and over the gill arches for ventilation.

Answer 175

cavity expands (the volume increases, which makes a lower pressure, making water rush into the mouth), and the operculum is closed when this is happening. Then, when the fish closes its mouth, the buccal cavity’s volume decreases, increasing pressure. The operculum opens, which pumps the water across the gills and out. So the duel pump system has 2 parts. 1) buccal cavity enlarging 2) water being pumped out over the gills It makes a near-constant flow of water across the gills.

Answer 176

Diffusion of oxygen A diffusion gradient is maintained all the way across the gill lamellae. Almost all the oxygen from the water diffuses into the blood. As blood flows in the opposite direction to the water, it always flows next to water that has given up less of its oxygen. Even after flowing down the length of the lamellae, there’s still a concentration gradient allowing it to absorb oxygen from water.

Answer 177

O2 and its conversion into energy. * The more energy required, the greater the selection pressure to increase the efficiency of O2 uptake and transport. * Solutions: - Increased surface area for gas exchange (gills) - Increased efficiency of O2 transport (incorporate circulatory system) - Increased O2 partial pressure difference (active ventilation, counter-current exchange) - Improved efficiency of ventilation (unidirectional)

Answer 178

* Problem: – Need to get O2 to cells * Solutions: – Take up O2 across epithelial surface, transport it to cells * Evolutionary consequences: – Selection favours efficiency: stronger selection where energy requirements (and therefore O2 requirements) are higher. * Air versus water: – Air has a higher O2 concentration and is less viscous.

Answer 179

Partial and total pressures change with altitude, but % composition remains the same.

Answer 180

High oxygen content Lower density and viscosity High diffusion constant for oxygen

Answer 181

The partial pressure of oxygen in the air at high elevations is lower than at sea level.

Answer 182

A. Cutaneous diffusion no circulatory system, circulatory system B. Tracheal systems (circulatory system not involved) C. Lungs (always involve the circulatory system) diffusion lungs tidally ventilated unidirectionally ventilated

Answer 183

eels. These eels can migrate from the straight to the ocean on land for 2-3 days. Gills are inefficient in air because of clumping of the filaments Oxygen uptake from the skin improves because of the higher oxygen content of air. They use gills in water and cutaneous diffusion on land.

Answer 184

Air has a higher O2 concentration than water

Answer 185

This is the most common type of air-breathing system due to there being 900,000 types of insects around (plus spiders and arthropods that use this system). They have 10 pairs of spiracles arranged along the segments of the body, these spiracles open at the body surface. These lead to a system of air tubules/the trachea, they become finer. Tracheae terminate in tracheoles. Tracheoles are the sites of gas exchange. Air is taken right up to cells to supply the mitochondria

Answer 186

The mantle cavity is the lung (where the diffusion happens), and the pneumostome is where air comes in. Because it’s diffusion the animal cannot uptake more air, it’s always the same amount.

Answer 187

‘book lungs’.

Answer 188

We don’t have problems with high energy use for breathing because air has less viscosity than water, so we can breathe in with less effort. This mechanism of breathing gives us high amounts of energy. There are many different organisms with ventilated lungs, so the breathing mechanism differs slightly in many of them.

Answer 189

Frogs have a buccal pump that gives them buccal breathing (2 processes happen) Their lungs are inflated through positive pressure, the air is pushed into the lungs. Inspiration: - nostrils open - buccal cavity expands - nostrils close - buccal cavity contracts - glottis opens - lungs expand Expiration: - lungs contract - buccal cavity expands - notrils open - buccal cavity expands - glottis closes

Answer 190

Lungs are inflated through negative pressure. Air inhaled. Rib cage expands as the rib muscles contract. Diaphargm contracts (moves down) Air exhaled. Rib cage gets smaller as the rib muscles relax. Diaphargm relaxes (moves up)

Answer 191

pulmonary artery

Answer 192

Birds have very high metabolic needs compared to other mammals as they fly high. So they need to get oxygen in and carbon dioxide out quickly. There’s no mixture of air, more complex again. They use a series of air sacs that allow for the movement of air across the lungs from posterior to anterior. There is unidirectional airflow through the lungs all of the time, there’s also crosscurrent blood flow across the lungs (to facilitate gas exchange).

Answer 193

diaphragm, but the chest cavity expands, resulting in a lower pressure so air flows into the trachea, going from there to the posterior air sac (not the lung).

Answer 194

gas exchange at all; they are used to push the air around. Bird lungs cannot expand and collapse, they are rigid. The air is always going in one direction whenever the bird is breathing in or out, from the posterior to the anterior air sacs.

Answer 195

the tracheal system of an insect

Answer 196

- Increase surface area for gas exchange (lungs) - Bring respiratory medium (air) directly to cells (tracheal in insects) - Increased partial pressure of O2 (active ventilation, cross-current exchange) - Improved efficiency of ventilation (tidal & unidirectional)

Answer 197

Transport function (transports nutrients, oxygen, waste, signalling molecules, heat). While in worms and molluscs, the fluid in their circulatory system serves as a hydrostatic skeleton.

Answer 198

interstitial fluid, it bathes/surrounds the organs. It can also serve as a hydrostatic skeleton, as it gives support to the body. The dorsal tubular hearts pump the fluid out into the organs, when it relaxes, the ostia open and the fluids are sucked back into the tubular hearts to be pumped around again.

Answer 199

the vessels also allow for more targeted delivery of blood. They also carry a pigment (hemocyanin) to which the oxygen binds. Overall, the crayfish has more ‘control’ of where the blood goes. Their circulatory system is used for gas exchange. These are all arteries, there are 3 connected sinuses where the blood drains into to get taken back to the heart to be pumped again

Answer 200

network where it fully carries blood to and from the heart. The blood is disconnected from the interstitial fluid. The earthworm has a dorsal heart and 5 auxiliary hearts (these pump the blood from the dorsal heart to the ventral vessels). Closed circulatory schemes of vertebrates All vertebrates have closed circulatory systems with a single heart responsible for pumping blood around the body. These can be a single or a double circuit.

Answer 201

sinus venosus at very low pressure. It then goes into the atrium, the atrium pumps it into the ventricle. As the ventricle is the main pump, it pumps blood via the conus of arteriosus into the aorta, where it goes into the gills. Gas exchange takes place, and a lot of pressure is lost. It continues through the rest of the body (losing more and more hydrostatic pressure) before going back to the heart (where there is virtually no hydrostatic pressure left in the blood flow). The heart contracting in the pericardial cavity creates enough negative pressure for the blood to be sucked back into the sinus venosus then back into the atrium to be pumped to the ventricle and so on.

Answer 202

ventricle. In the centre of the heart, there is a mixing of the deoxygenated and the oxygenated blood (about 10% mixing). It also mixes in the capillaries. In the left ventricle, there is a spiral valve that directs most of the oxygenated blood into the aorta. Unlike fish, there is a pulmocutaneous circuit. The left ventricle pumps deoxygenated blood to the lungs and skin, where gas exchange takes place. The oxygenated blood returns to the heart and gets pumped to the organs/the rest of the body. In this simplified loop, the blood can bypass the lungs completely, which is needed when the frog is underwater and the lungs cannot work there (the skin becomes the sole organ for gas exchange). This is a double circuit as the blood goes through the heart twice, it also evolved at the same time as lungs.

Answer 203

ventricles, but it’s still not a complete separation. So there’s a lot less mixing of the oxygenated and the deoxygenated blood. There’s an extra circuit (in purple) called the right systemic aorta. This allows them to bypass the lungs, a useful thing for these animals as they can spend hours underwater. Being underwater lowers their metabolic demand, so they are able to oxygenate without their full capacity (the lungs). This circuit of deoxygenated, mixed blood passes through the gut, so there’s a theory that this deoxygenated blood that’s high in CO2 aids in digestion.

Answer 204

heart. The chambers are all separated, there is no mixing of deoxygenated and oxygenated blood in the heart. There is double circulation from the amphibians onwards. Double circulation means much higher pressure, blood gets delivered to organs and extremities under this higher pressure. This allows for faster lifestyles as mammals and birds have much higher energetic demands, which is important. With a mammal and a reptile of the same size, the mammal will have 10x the metabolic rate of the reptile.

Answer 205

A closed circulatory system

Answer 206

carry blood away from the heart – oxygenated (systemic circuit) or deoxygenated (pulmonary circuit) blood – thick-walled and elastic – smooth out pressure pulses of the beating heart.

Answer 207

– finest arterial branches – smooth muscle in the wall controls tissue blood flow locally

Answer 208

– finest vessels – thin permeable walls – site of gas and nutrient exchange with the tissues

Answer 209

– smallest branches of veins – collect blood from capillaries

Answer 210

carry blood towards the heart – oxygenated (pulmonary circuit) or deoxygenated (systemic circuit) blood – thin-walled – contains most of the blood – Veins in the extremities contain valves to maintain the direction of flow

Answer 211

of its valves.

Answer 212

Because a four-chambered heart has complete separation of oxygenated and deoxygenated blood.

Answer 213

vena cava → right atrium → right ventricle → pulmonary artery

Answer 214

gases, nutrients, waste, hormones and other substances around the body.

Answer 215

* O2 transport is the major function in most (not all!) animals, and selection will favour animals with greater efficiency at transporting O2. * Solutions: – Separation of blood and body fluids (closed system) – Dedicated oxygen carriers (e.g., hemoglobin) – Separation of oxygenated and deoxygenated blood – Double circuit to increase blood pressure through tissues. * Open systems are less efficient at delivering O2, but also require much less energy to build and maintain, so they are an optimum solution where O2 transport is not required.

Answer 216

Osmoregulation. This is maintaining water/salt balance. Freshwater fish need to maintain their high levels of salt, so they produce large volumes of dilute urine. Sea water fish need to keep water in and not salts, producing high volumes of very salty, concentrated urine. This makes the freshwater fish hyperosmotic and the seawater fish hypo-osmotic.

Answer 217

Excretion of Nitrogenous waste.

Answer 218

tubular design

Answer 219

urine): Protonephridia: – Flatworms, rotifers, larval annelids and molluscs Malpighian tubules: – Insects, spiders, centipedes Metanephridia and coelomoducts: – Annelids (earthworms), molluscs, crustaceans, vertebrate kidney

Answer 220

Lungs, gills, salt glands, skin

Answer 221

Urine formation: beating of cilia of 'flame bulb' draws H2O + solutes into tubule (filtration). Valuble solutes reabsrobed into tubule. Urine low in solutes, balances H2O uptake.

Answer 222

Primary urine formation: Active transport of potassium and salts into tubule. Water flows by osmosis, generating urine flow. Uric acid comes out (insoluble)

Answer 223

Each body segment has a pair of metanephridia, which are immersed in coelomic fluid and enveloped by a capillary network. Salts reabsorbed producing dilute urine * More advanced than protonephridia because: – Open system (open both ends), faster urine formation. – Surrounded by a network of blood vessels to adjust the composition of urine. * The basic process of urine formation same: – Fluid constantly entersthe tubule. – Selectively modified by withdrawing valuable solutes (reabsorption), adding wastes (secretion). Coelomoducts/kidneys same process but with initial ultrafiltration.

Answer 224

The renal arteries supply the kidneys with about 20% of the output of the heart. Between 1,100 and 2,000 litres of blood flow through a pair of human kidneys each day (275 times total blood volume!). Regulate: osmolarity of blood, Na/K ratio of plasma, blood volume, blood pressure by adjusting rate and composition of urine formation

Answer 225

Initial filtrate (salts, sugar, amino acids)

Answer 226

The kidney is able to adjust the rate of urine formation and urine composition Mammals can produce urine either more dilute or more concentrated than the blood – adaptations to terrestrial life These adjustments are controlled by hormones (primarily antidiuretic hormone and aldosterone) ADH, dehydration and urine concentration Hormones control urine dilution – antidiuretic hormone affects the water permeability of the collecting ducts. More permeability = more water reabsorption = more concentrated urine Less hormone = less water permeability – more water retained in urine.

Answer 227

lives in desert environment with very little drinking water available. Problem: water conservation. Solution: extremely concentrated urine. Nephrons have extremely long loops of Henle to maintain steep osmotic gradients.

Answer 228

lives in fresh water. Dehydration is not a problem. So have very short loops of Henle, and have very little ability to concentrate urine.

Answer 229

kidneys similar to mammals but with much shorter loops of Henle. Problem: water conservation. Solution: produce uric acid which can be excreted as a paste, rather than urea which must be dissolved in water.

Answer 230

no loops of Henle, so cannot concentrate urine. Problem: water conservation. Solution: produce uric acid (like birds) and reabsorb water across epithelium of cloaca.

Answer 231

Lives in freshwater, hyperosmotic to surroundings. Problem: excess water take up across the gills. Solution: very dilute urine.

Answer 232

Kidneys function much like those of freshwater fish. Kidneys excrete dilute urine in fresh water, but reabsorb water across the bladder when on land to conserve water.

Answer 233

hypo-osmotic to seawater. Problem: lose water across the gills and gain salts. Solution: nephrons with small glomeruli, no distal tubule, and very few nephrons in the kidney. The main function of the kidney is excretion of double-charged salts (Ca2+, Mg2+, SO42-). Drinks lots of water and produces very little urine.

Answer 234

Vampire bats feed on blood. i.e. they take in a large amount of liquid that needs to be eliminated so they are light enough to fly. But: little drinking water in their roosting sites (caves, hollow trees). When feeding, they produce dilute urine to get rid of excess water from the blood meal. When roosting, they produce very concentrated urine to get rid of nitrogenous waste while conserving water (up to 4,600 mosm/L).

Answer 235

excrete large quantities of water

Answer 236

Protonephridia

Answer 237

Digestive tube

Animals Flashcards

(274 cards)